Capital Transactions - Summary of Shares Issued and Proceeds Received in Connection with Offerings (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Investment Company, Capital Share Transactions [Line Items]
Proceeds to Company	$ 1,751	$ 887	$ 3,316	$ 1,645
Shares (in shares)			2,717	2,342
Net Proceeds to Company			$ 85,242	$ 70,500
Average Net Proceeds per Share	$ 31.36	$ 30.11	$ 31.36	$ 30.11
Receivable for shares sold		$ 12,100		$ 12,100
Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)			2,611	2,286
Gross Proceeds			$ 83,097	$ 69,681
Sales Load			(1,171)	(826)
Net Proceeds to Company			$ 81,926	$ 68,855
Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)			106	56
Proceeds to Company			$ 3,316	$ 1,645
Class A
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)			301	210
Net Proceeds to Company			$ 9,371	$ 6,230
Average Net Proceeds per Share	31.15	$ 29.73	$ 31.15	$ 29.73
Class A | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)			276	189
Gross Proceeds			$ 9,250	$ 6,053
Sales Load			(659)	(446)
Net Proceeds to Company			$ 8,591	$ 5,607
Class A | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)			25	21
Proceeds to Company			$ 780	$ 623
Class T
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)			359	273
Net Proceeds to Company			$ 11,164	$ 8,139
Average Net Proceeds per Share	31.14	29.77	$ 31.14	$ 29.77
Class T | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)			342	266
Gross Proceeds			$ 11,154	$ 8,304
Sales Load			(512)	(380)
Net Proceeds to Company			$ 10,642	$ 7,924
Class T | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)			17	7
Proceeds to Company			$ 522	$ 215
Class D
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)			371	175
Net Proceeds to Company			$ 11,445	$ 5,155
Average Net Proceeds per Share	30.78	29.52	$ 30.78	$ 29.52
Class D | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)			360	169
Gross Proceeds			$ 11,093	$ 4,996
Sales Load			0	0
Net Proceeds to Company			$ 11,093	$ 4,996
Class D | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)			11	6
Proceeds to Company			$ 352	$ 159
Class I
Investment Company, Capital Share Transactions [Line Items]
Shares (in shares)			1,686	1,684
Net Proceeds to Company			$ 53,262	$ 50,976
Average Net Proceeds per Share	$ 31.57	$ 30.27	$ 31.57	$ 30.27
Class I | Proceeds from Public Offering
Investment Company, Capital Share Transactions [Line Items]
Shares issued (in shares)			1,633	1,662
Gross Proceeds			$ 51,600	$ 50,328
Sales Load			0	0
Net Proceeds to Company			$ 51,600	$ 50,328
Class I | Distribution Reinvestment Plan
Investment Company, Capital Share Transactions [Line Items]
Issuance of common shares through distribution reinvestment plan (in shares)			53	22
Proceeds to Company			$ 1,662	$ 648